Polymer waste (scrap) materials containing a substantial volume of an inorganic filler component are typically disposed of via land fill. Such polymer waste materials have included filled/unfilled thermoset/thermoplastic polymers, exemplary of which are reinforced reaction injection molded (RRIM) theromset plastic materials having a urethane organic component as well as unreacted precursors (e.g., polyols and isocyanates) of the RRIM polymer; sheet molding compounds (SMC) having a styrene cross-linked polyester organic component; uncured SMC reactants (commonly called "purged SMC)" comprising styrene and unsaturated polyesters; and such epoxies, phenolics, silicates, melamines, diallylphthalates, and polyimides as are typically used in reinforced plastics. The polymer waste material also includes used (scrap) vehicle tires and car fluff which comprises the residue of a scrap vehicle after being processed to remove metal (e.g., steel, iron, copper, aluminum). Car fluff typically comprises approximately 50-60 weight % organics and the balance inorganics such as mostly rust (e.g., 35-40 weight %), glass, grid and dirt.
Disposal of such waste polymer materials by land fill is fraught with environmental problems relating to a lack of land fill space and the inability of polymers to rapidly degrade at the land fill site. Moreover, land fill disposal of such polymer waste materials can be costly as a result of transportation and handling costs involved and as a result of disposal fees charged for certain waste polymer material. For example, disposal of used tires at a land fill site in the state of Michigan requires a disposal fee of one dollar per tire, whereas disposal of used tires in the state of Minnesota requires a disposal fee of five dollars per tire.
A known alternative to disposing of such waste polymer material by land fill involves pyrolyization to volatize the organic component from the inorganic component of the material. Pyrolysis is the thermal decomposition of organic matter at temperatures sufficient to volatize or gasify organic matter in the feed in the absence of oxygen or any oxidizing agent. Copending U.S. application Ser. No. 07/655,920, now U.S. Pat. No. 5,129,995 entitled PYROLYSIS PROCESS AND APPARATUS and of common assignee herewith describes a continuous pyrolysis apparatus and method for recovering the inorganic component from such waste polymer materials for reuse in the manufacture of like material and the organic component as gaseous decomposition products for use in fueling the pyrolysis apparatus; i.e., for combustion in the burner of the pyrolysis apparatus.
In view of the ever increasing amount of waste polymer materials generated by a wide variety of industries throughout the world, there is a need for disposal of large quantities of such waste materials in an environmentally acceptable and cost effective manner. Disposal of such waste materials in a manner that can recover at least some of their energy value would be highly advantageous and desirable to reduce energy demand.
It is an object of the present invention to provide a method of making iron wherein solid waste polymer material is charged to an iron-making vessel for combustion of the waste polymer material therein as a substitute for more costly fuel that would otherwise be required to heat and melt an iron-bearing material in the vessel, whereby the waste polymer material is disposed of while recovering at least some of its heat (energy) value.
It is another object of the present invention to provide a method of making iron wherein waste polymer material containing a calcium carbonate filler is charged to an iron-making vessel for combustion of the waste polymer material therein as a substitute for more costly fuel that would otherwise be required to heat and melt an iron-bearing material in the vessel and also to release the calcium carbonate for participation in the iron-making method as a flux for removing impurities from the iron melt, whereby the waste polymer material is disposed of while recovering at least some of its heat (energy) value and reusing the calcium carbonate therein for fluxing purposes.
It is still another object of the present invention to provide a method of making iron wherein at least a portion of the fuel burned to heat and melt an iron-bearing charge material in an iron-making vessel comprises gaseous decomposition products from pyrolysis of waste polymer material, whereby the waste polymer material is disposed of while recovering at least some of its heat (energy) value.